At present, the application field of Force Touch is becoming wider and wider. Currently, Force Touch is achieved mainly in following three implementations:
In the first implementation, a pressure sensor is added on the back or in the middle frame of a touch display module, when an external pressure F is applied to the touch display module, and Force Touch is achieved through detecting the amplitude of the external pressure F by means of the pressure sensor. The first implementation may increase production costs and occupies the assembling space of the final product.
In the second implementation, it is a product having an add-on touch module with adhesive. The cover of the product is laminated through adhesive. An air gap exists between a finger and detection electrode(s) and the signal becomes lower during detecting, and the non-uniform deformation of the adhesive under the pressure force leads to non-uniform pressure detection between the edge region and the central region. This implementation is mainly used for the low end products, and many restrictions exist in pattern and thickness.
In the third implementation, a sensing layer is attached to the back of a backlight, because the capacitive pressure detection mainly detects the deformation, and the deformation of the middle frame with respect to the sensing layer is the largest under pressure, thus Force Touch is achieved through detecting the deformation of the sensing layer with respect to the middle frame. The third implementation will also increase the production cost and occupy the assembling space of the final machine.
In summary, when the above technical implementations are used for achieving Force Touch, the production costs become higher and the larger assembling space of product will be occupied.